Tough stable-surface alloy steel



-'ties.

Patented Nov. 4, 1924.

urrso STA mm a. n. new YORK, assrenons,

l- STRONG, 0F LOUDONVILLE. AND RALPH P. DE VEIFS, 0F NEWTON- BY DIRECT AND MESNE ASSIGNMS, 'm LUD- LUH STEEL COMPANY, OF wernnvmn'r, NEW YORK, A. CORPQMTION 0? NEW TOUGH STABLE-SURFACE ALLQY ST.

Kc Drawing.

To all whom it may concern."

Be it known that we, PERCY A. .E. Almis'raoxo, a subject of the Kin of Great Britain, and a resident of Lou onville, county of Albany, and State of New York, and RALPH P. lDE VRIEs, a citizen of the United States, anda resident-of Newtonville, county of Albany, and State of New York. have invented a new and useful Tough Stable-Surface Allo Steel, of which the following is a speci cation.

The invention relates to alloy steel. The allo steel of the present invention has high sur ace stability, that is to say, has high V resistance to agents tending to produce corroding, rusting, staining and thelike, and also is markedly high in toughness and mechanical strength as indicated by ductility and impact tests, for example, making it particularly valuable for wrought metal articles which are to have high mechanical strength as well as highly stable surface characteristics.

The improved alloy steel contains principally iron, carbon, chromium, silicon and nickel, with more or less traces of man-v ganese, phosphorus, etc., which are present in substantially all steels. With stable surface alloy steel containing princi ally iron, carbon, chromium and silicon as disclosed in Patent No. 1,322,511 of Nov. 25th, 1919, to said Armstrong, the addition of nickel is of relatively small importance so far as the stable surface characteristics of the alloy steel are concerned, though as is stated therein, some nickel can be added without substantial detriment to the stable surface quali- Where high mechanical 'stren h and toughness are of importance as wel as high surface stability, we substitute another metal of the iron group, referably, nickel, for

4 part of the iron in tlie alloy of said Armstrong patent, thereby increasingthe toughness of the alloy. Any tendency toward loss of surface stability produced by the substitution of nickel for part of the iron, such as results to some extent, for example, in re .spect to degree of resistance to rusting and to the action of strong nitric acid, is compensated where tough material is requir d Application filedl February 3, 1m. Serial aa'aereai,

by the increasfi toughness obtained. V'Vben the proportion of silicon is increased along with the substitution of nickel for a art of the iron tougher material can be 0 tained with ractically no loss whatever of surface stability.

This can best be understood from the following example: An alloy steel containing carbon .5%, chromium 17%, silicon 2%, an the rest principally iron has better resistance to rusting than the same alloy with 15-25% of nickel and correspondingly less iron, but the toughness of the latter alloy is greater. With increase of the silicon to about 5% and without the nickel, an alloy is obtained of extremely high surface stability, but its physical properties are not so good as with the lower silicon. If 15-25% of nickel is incorporated in this last material in the place of a corresponding quantity of iron, giving an alloy containing carbon .5%, chromium 17%, silicon 5%, nickel 15-25%, and the remainder principally iron, the surface stability, while reduced as compared with the same material without the nickel, isabout as good as with the alloy firstnamed in this paragraph, and the material is tough, and while comparatively hard to machine can nevertheless be machined with the use of the proper. tools.

The carbon of the alloy steel should be from about ,05% to about .50%. Where the carbon is hi h, nickel does not add substantially to 510 toughness of the alloy steel.

The silicon content of-the alloy steel is from about .75% to about 6% and preferably from about 1.5% to about 4.5%. With less than .75% the stable surface eflect of silicon is relatively inconsiderableand ,,with

silicon above about 6%, the desirable totigh- .ness is reduced.

The chromium may be from about 5% to about 25%.

The nickel may be from about 4% to about. 30%, replacing a corresponding amount of iron.

Some examples of good alloy steel within the scope of our invention are 'ven in the following table which is inten dd to serve only as affording an understanding of some 0i al y steels within the scope of the thereto:

invention and not for limitationof the in vention:

Chro- Carbon. mmm' Silicon. Nickel. Iron.

Per Per Per Per cent. rent. cent. cent.

. 40 17 3 15 Principal part of remainder. 35 l6- 4. 5 16 Principal part of remainder. .50 16 5 20 Principal part oi remainder. 55 i2 4 25 Principal part of remainder. 30 20 8. 5 30 Principal part 0! remainder. 30 8 2 10 Principal part of remainder. 40 5 3 15 Principal part otremalnder.

The alloy steel of the present invention,- particularly with over about 8% of nickel, appears to be generally austenitic in character. Sharp cutting tools should be used in machining it, and any rubbing action such. as

takes place in sawing for exam le, is preferably to.be avoided. It shou d be noted 7 that the inclusion of nickel in the allo steel makes 1t more non-magnetic, and t at in general in order to obtain equivalent stable tenite that it can be more readily machined than is the case where the same nickel and chromium are used with lower vsilicon. Where the allo steel without" the nickel does not tarnis upon exposure to weak acids such as vine ar, fruit juices and the like, and particular y where it contains over 13% of chromium and silicon taken together, the replacement of a ort ion of the non by nickel as described erem to produce increased toughness may be carried out without causing the material to tarnish under such conditions.

The alloy steel of the present invention is adapted for a large number of uses requiring surface stability and toughness. Among numerous other uses, the following may be briefly referred to, but without hmitation turbine bucket blades, ball bearings, balls, glass molds, shafts for machin'- ery, cutlery, acid resisting material, nonmagnetic steels, automobile valves, rifle barrels, heat resisting material and electrical resistance elements. The specific resistance of the alloy steel of the'present invention is about the same as that ofthe allo steel of the Armstrong patent above re erred to. The substitution of nickel for part of the iron does not appear to produce material about 25%, silicon from about 1.5% to about 6%, nickel from about 4% to about 30%, and the principal portion of the remainder iron.

2. A tough alloysteel having high surface stability, containing carbon about 05% to about .50%, chromium from about 8% to about 20%, silicon from about 1.5% to about 4.5%, nickel from about 4% to about 30%, and the principal portion of the remainder iron.

3. A tough alloy steel of high surface stability, comprising carbon from about .05% to about .5%, chromium from about 15% to about 20%, silicon from about 1.5% to about 4.5%, nickel from about 15% to about 30%, and the principalportion of the remainder iron.

4. Tough stable surface alloy steel comprisin carbon about .05% to about 50%, chronnum about 17%, silicon from about 1.5"; to about 5%, nickel about 15% and the principal portion of the remainder iron.

5. VVrou ht metal articles havin high surface sta ility and toughness, an made from alloy steel in accordance with claim 1.

6. Wrought metal articles havin hi h surface sta llity and toughness, an ma e from alloy steelin accordance with claim 2.

7. Wrou ht metal articles -havin surface sta ility and toughness,-an' ma e from alloy steel in accordance with claim 3.

8. Wrou ht metal articles havin high surface sta ilit and tou'ghness, an made from alloy stee in accordance with claim 4.

In testimony that we claim the foregoing, we have si ed our names hereto.

' ERGY A. E. ARMSTRONG..

RALPH P. DE VRIES. 

